n = input()
k = input()
 
a = k.count("R")
print(k[:a].count("W")) n = input() n input() input k = input() k input() input a = k.count("R") a k.count("R") k.count k count "R" print(k[:a].count("W")) print k[:a].count("W") [:a].count [:a] k :a a count "W" k = input() input() k a = k.count("R") k.count("R") a n = input() input() n
n = input()
k = input()
 
a = k.count("R")
print(k[:a].count("W"))